The Incas used trapezoids for all their windows and doors, which withstand earthquakes well.

# Quadrilaterals: Theorems and Problems 5

Proposed Problem 312.

Proposed Problem 280.

Proposed Problem 273.
Triangle, Perpendiculars, Area of Squares.

Proposed Problem 252.
Parallelogram, sides, diagonals, squares, areas.

Proposed Problem 251.
Parallelogram, sides, diagonals, squares, areas.

Proposed Problem 250.

Proposed Problem 245. Parallelogram with Equilateral triangles

Proposed Problem 244. Square, Diagonals, Centers, Distance.

Proposed Problem 243. Triangle with Equilateral triangles, Parallelogram.

Proposed Problem 242. Triangle with Equilateral triangles, Parallelogram.

Proposed Problem 240. Triangle with Equilateral triangles, Parallelogram.

Proposed Problem 239. Square, Midpoints, Lines, Congruence, Pythagoras.

Proposed Problem 238. Square, Midpoints, Lines, Congruence.

Proposed Problem 237. Quadrilateral, Midpoints, Exterior line, Perpendicular lines.

Proposed Problem 236. Quadrilateral, Midpoints, Exterior line, Perpendicular lines.

Proposed Problem 235. Parallelogram, Transversal line, Perpendicular lines.

Proposed Problem 234. Parallelogram, Line through a vertex, Perpendicular lines.

Proposed Problem 233. Parallelogram, Exterior line, Perpendicular lines.

Proposed Problem 232. Parallelogram, Line through a vertex, Perpendicular lines.

Proposed Problem 230. Triangle, Midpoints, Transversal, Perpendicular lines.

Proposed Problem 229. Triangle, Centroid, Transversal, Perpendicular lines.

Proposed Problem 228. Triangle, Midpoints, Exterior line, Perpendiculars lines.

Proposed Problem 227. Triangle, Centroid, Exterior line, Perpendicular lines.

Proposed Problem 226. Triangle, Centroid, Perpendiculars.

Proposed Problem 225. Viviani's Theorem Extension, Regular Polygon, Apothem, Distance.

Proposed Problem 219. Rhombus, perpendiculars, arithmetic mean.

Proposed Problem 216. Quadrilateral, Angle Bisectors, and Concurrency.

Proposed Problem 214. Quadrilateral and Angle Bisectors.

Archimedes Arbelos and Square 2. Dynamic Geometry Software.
Step-by-Step construction, Manipulation, and animation.

Archimedes Arbelos and Square 1. Dynamic Geometry Software.
Step-by-Step construction, Manipulation, and animation.

Proposed Problem 198. Triangle, Quadrilateral, Angles.

Proposed Problem 191. Triangle, Altitudes, Orthocenter, Squares, Areas.

Proposed Problem 189. Squares, Distances.

Proposed Problem 188. Square, Diagonal, 45 Degrees Angle.

Proposed Problem 185. Trapezoid, Triangles and Angles.

Proposed Problem 184. Triangle and Angles.

Proposed Problem 181. Circular Sector of 90 degrees, find an angle.

Proposed Problem 179. Rhombus, Square, Diagonal, Angle.

Proposed Problem 178. Quadrilateral, Trisection of sides, Area.

Proposed Problem 177. Parallelogram with Midpoints, Triangles, Areas.

Proposed Problem 176. Quadrilateral with Midpoints, Triangles, Areas.

Proposed Problem 175. Quadrilateral with Midpoints, Areas.

Proposed Problem 174. Quadrilateral with Midpoints, Triangles, Areas.

Proposed Problem 173. Quadrilateral with Midpoints, Triangles, Areas.

Proposed Problem 172. Trapezoid, Midpoints, Quadrilaterals, Areas.

Proposed Problem 171. Trapezoid, Midpoints, Triangles, Areas.

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 Home | Geometry | Polygon | Trapezoid |Triangle and Squares | Email | By Antonio Gutierrez Last updated: May 7, 2009